A slot is a narrow, elongated depression, groove, notch, or slit, especially one for receiving or admitting something, such as a coin or a letter. Also used in a computer to describe an opening into which a memory card or other device can be fitted to provide additional capability. (Linguistics) A position having a specific grammatical function within a construction into which any of a number of morphemes or morpheme sequences can fit.

A casino game that involves spinning reels to win credits based on combinations of symbols. A slot can be a standalone machine, or part of a progressive jackpot system that can reward players with large payouts. A slot can have a themed theme, and the symbols are usually aligned with that theme.

Charles Fey invented the modern three-reel slot machine in 1899. His machine allowed automatic payouts and featured symbols such as spades, hearts, horseshoes, and stylized lucky sevens. It is regarded as the first true mechanical gambling machine. The Liberty Bell was the highest-paying symbol on his machine and earned it its name. A plaque marks the location of Fey’s San Francisco workshop.

In aviation, a slot is an authorization to take off or land at a specific airport during a specified time period. The term is most often used to refer to the time allotted to a single aircraft, but it can also refer to a block of times reserved for a particular class of flight or air traffic control clearance.